Matrix printer with overlapping print dots

ABSTRACT

A matrix printer head apparatus and method of printing have been devised for high-speed printing operations in which impressions or dots formed on the print medium will overlap to form apparent solid lines. Overlapping of impressions or dots both in the horizontal and vertical directions in high-speed printing operations is accomplished by a novel and improved arrangement of the print elements and the manner in which the print elements are incrementally advanced and positively driven in forming each matrix.



1. A matrix printer head comprising in combination: a plurality of print members having impression elements arranged in adjacent columns and disposed in confronting relation to a print medium, the impression elements in one column being offset vertically and laterally with respect to the impression elements in an adjacent column, said impression elements adapted to impress a matrix of dots to form each character on the print medium, print member drive means for sequentially driving selected of the print members in each column to advance their impression elements forwardly into contact with the print medium whereby the dots formed in one column are vertically and laterally offset with respect to dots formed by the next adjacent impression elements of the adjacent column, and printer head advancing means for incrementally advancing said printer head in a direction laterally of the print medium to a succession of incremental positions in forming each character, the distance between incremental positions corresponding to the spacing between adjacent columns of said impression elements, said print member drive means sequentially driving selected of the print memberS in each column at each incremental position whereby the dots formed by driving selected of said print members in one column by said print member drive means will partially overlap and be vertically aligned with the next adjacent dots previously formed by driving of the print members of the adjacent preceding column at that incremental position, so that characters having apparent solid lines are formed by the matrix of dots when the printer head has been successively advanced through a series of incremental positions in forming each character.
 2. A matrix printer head according to claim 1 including timing means between said print member drive means for the print members in each column to sequentially drive the print members in one column a predetermined time interval after driving the print members of the other column into contact with the print medium at each incremental position.
 3. A matrix printer head according to claim 1, said drive means for each print member including forward drive means for driving each print member to advance the impression elements into contact with the print medium, and reverse drive means for positively driving each print member and associated impression elements away from the print medium.
 4. A matrix printer head according to claim 1 wherein the impression elements are arranged in a pair of spaced adjacent columns, one column of impression elements being offset less than a full dot width apart from the impression elements in the other column.
 5. A matrix printer head according to claim 1 wherein the impression elements in each column are laterally offset less than a full dot width apart, and said impression elements in one column are spaced equal distances between adjacent impression elements in the other column.
 6. A matrix printer head according to claim 5, said impression elements in the adjacent columns being operative to form an overlapping series of dots vertically along each column printed in a matrix and an overlapping series of dots horizontally and diagonally between columns as said print members are successively advanced to each incremental position and selected of said impression elements are sequentially advanced into contact with the print medium.
 7. A matrix printer head according to claim 1 wherein said print members include a plurality of elongated flexible print wires, each of the print wires having a leading end terminating in an impression element at one end and a trailing end portion at the opposite end, said print member drive means having actuator assemblies at the trailing ends of said print wires, each actuator assembly including an armature at the trailing end of each print wire, electromagnetic forward drive means adjacent to the forward end of each armature operative to energize said armature to drive each said print wire in a forward direction, electromagnetic reverse drive means aligned adjacent to the rearward end of said armature operative to energize said armature to positively drive each said print wire in the reverse direction, and timer means for successively energizing said electromagnetic forward and reverse drive means of each actuator assembly to positively advance and retract said print wires toward and away from the print medium, respectively.
 8. A matrix printer head according to claim 7, said actuator assemblies including at least one centrally disposed actuator assembly and a plurality of actuator assemblies arranged in a circle about the central actuator assembly, said print wires converging forwardly from the trailing end portions and the leading ends of said print wires extending horizontally in closely spaced, parallel relation to one another.
 9. In a matrix printer head adapted for impressing a matrix of dots to form each character on a printing medium, the combination comprising: a plurality of elongated, axially movable print members each provided with a leading end portion having an impression surface at its leading terminal end and a trailing end portion including an actuator assembly, there being at least one actuator assembly disposed centrally with respect to the other actuator assemblies, and the other actuator assemblies disposed in a circle at equally spaced circumferential intervals in surrounding relation to the centrally disposed actuator assembly, each actuator assembly including positive forward and reverse drive means at opposite ends thereof and means for successively energizing said forward and reverse drive means, said print members converging forwardly from said actuator assemblies and terminating in leading end portions which extend in spaced parallel relation to one another, and a guide post provided with a series of closely spaced apertures arranged in spaced adjacent columns to receive and guide the leading ends of said print members for movement toward and away from the print medium, actuator control means associated with said forward and reverse drive means for sequentially driving selected of the print members in each column to advance their impression elements forwardly into contact with the print medium whereby the dots formed by one column of print members will touch the next adjacent impression elements of the adjacent column, printer head advancing means for incrementally advancing said printer head in a direction laterally of the print medium to a succession of incremental positions in forming each character whereby the dots formed by driving selected print members of said actuator control means in one column will touch and be vertically aligned with the next adjacent dots of the preceding series of dots formed by the adjacent column of print members at incremental positions whereby characters having apparent solid lines are formed by the matrix of dots when the printer head has been successively advanced through a series of incremental positions.
 10. In a matrix printer head according to claim 9 including a common mounting plate for said actuator assemblies and printer head support means for guiding and supporting said print members for forward extension from said mounting plate through guide passages in said printer head support means, said guide post positioned at the leading end of said printer head support means.
 11. In a matrix printer head according to claim 10, the guide passages of said printer head support means each having a low coefficient of friction tube lining the wall of said passage for extension of a print member therethrough, and the guide passages terminating in a common recess for extension of the leading ends of said print members therethrough.
 12. In a matrix printer head according to claim 11, said print head support means including said guide post at the leading end thereof in front of the recess, said guide posts provided with apertures therein for reception of the leading ends of said print members.
 13. In a matrix printer head according to claim 12, the apertures in said guide post each defining a bearing surface for high-speed movement of a print member therethrough without contacting the other print members.
 14. A method of printing characters on a printing medium with a printer head having a series of print elements arranged in spaced adjacent columns comprising the steps of: arranging the print elements of one column in vertically offset relation to the print elements of the next adjacent column, selectively activating the print elements in one column to form vertically spaced impressions in a single column upon the print medium, incrementally advancing the printer head to a position in which the print elements of the other column are aligned in the plane through the impressions formed by the print element of the one column, and selectively activating the print elements of the other column to form impressions along the same column of impressions formed by the one column, the vertical distance between adjacent offset print elements of the columns being such that the impressions formed by offset adjacent print elements in a siNgle column will partially overlap to form an apparent solid line of print. 